$ { {4} \times \left[\begin{array}{rrr}{0} & {4} & {4} \\ {1} & {-2} & {1}\end{array}\right] = {?} } $
To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rrr}{4}\times{0} & {4}\times{4} & {4}\times{4} \\ {4}\times{1} & {4}\times{-2} & {4}\times{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{0} & {16} & {16} \\ {4} & {-8} & {4}\end{array}\right]}$